chore(plaintext): remove deprecated symbols

Pull-Request: #4734.

Author: thomaseizinger

transports/plaintext/CHANGELOG.md

@@ -2,6 +2,8 @@
 
 - Migrate to `{In,Out}boundConnectionUpgrade` traits.
   See [PR 4695](https://github.com/libp2p/rust-libp2p/pull/4695).
+- Remove deprecated type-aliases and make `Config::local_public_key` private.
+  See [PR 4734](https://github.com/libp2p/rust-libp2p/pull/4734).
 
 ## 0.40.1
 

transports/plaintext/src/lib.rs

@@ -47,21 +47,13 @@ mod proto {
     pub(crate) use self::structs::Exchange;
 }
 
-#[deprecated(note = "Has been renamed to `Config`.")]
-pub type PlainText2Config = Config;
-
-#[deprecated(note = "Has been renamed to `Output`.")]
-pub type PlainTextOutput<T> = Output<T>;
-
 /// [`Config`] is an insecure connection handshake for testing purposes only.
 #[derive(Clone)]
 pub struct Config {
-    #[deprecated(note = "Will be made private in the future, please use `Config::new` instead!")]
-    pub local_public_key: identity::PublicKey,
+    local_public_key: identity::PublicKey,
 }
 
 impl Config {
-    #[allow(deprecated)]
     pub fn new(identity: &identity::Keypair) -> Self {
         Self {
             local_public_key: identity.public(),